Name: ______Block: ______Date: ______
Activity #1
Biology Place: Solutions: Isotonic, Hypotonic, & Hypertonic
· Log on to www.biology.com
· Click on:
o The Biology Place (on the right side of the screen) à
o Biocoach à
o Biomembrane I: Membrane Structure and Function à
o Concept 2: Osmosis: Movement of Water Across Membranes (on the left side of the screen)
Osmosis (movement of water across membranes) depends on the relative concentration of solute molecules on either side of the membrane. The presence or absence of cell walls influences how cells respond to osmotic fluctuations in their environment.
Click on Review
Looking at the diagram above. Describe the difference between the three types of solutions.
The small circles represents dissolved solutes like salt, glucose, and amino acids. You can assume that the additional space surrounding the solutes is water.
hypotonic - ______
______
isotonic - ______
______
hypertonic - ______
______
Click on Next à Cells in Isotonic Solution
1. What is the concentration of salt in animal cells? ______
2. When cells are in isotonic solution, is there movement of water into or out of the cell? If so, describe this movement. ______
______
Click on Next à Cells in Hypotonic Solutions
Describe the net movement of water molecules when cells are placed in a hypotonic solution. ______
______
Click on A Closer Look à A Closer Look at Plant and Animal Cells in Hypotonic Environments
**Make sure to ANIMATE the graphics.**
What happens to an animal cell when placed in a hypotonic solution?
______
Click à Back to Review then Next à Cells in Hypertonic Solutions
Describe the net movement of water molecules when cells are placed in a hypertonic solution. ______
______
Activity #2
Log on to: http://www.concord.org/~btinker/workbench_web/models/osmosis.swf
Play with the model by putting the cell in isotonic, hypertonic, and hypotonic solutions. Don’t forget to hit “Reset” and “Update Concentrations” after you adjust intracellular and extracellular contents. Observe how the cell changes or does not change under each condition. Then answer the following questions:
Why do hospitals treat dehydrated patients with intravenous saline solution and not water? Explain. ______
______
______
What would be the health effects if someone lost at sea only drank sea (salt) water for a prolonged period? ______
______
______
Practical Applications of Osmosis:
Based on what you have learned about osmosis, find literature resources to help you describe how the following chemicals act as regulators of osmosis in human organ-systems:
Caffeine
______
______
Sodium Chloride (table salt)
______
______
Hydrochlorothiazide (blood pressure medication)
______
______
Based on what you have learned about osmosis, find literature resources to help you describe how semi-permeability is very important in membranous systems:
The brain’s blood barrier
______
______
Absorption through the skin of various substances
______
______
Peritoneal dialysis for patients with diseased kidneys
______
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